The present invention relates to the field of communications and more particularly to methods and receivers for receiving signals transmitted with transmit diversity.
A two branch transmit diversity scheme for channels without intersymbol interference is discussed by S. M. Alamouti in the reference entitled xe2x80x9cA Simple Transmit Diversity Technique For Wireless Communications,xe2x80x9d Journal Of Selective Communications, vol. 16, no. 8, pp. 1451-1458. With two transmit antennas and one receive antenna, second order diversity may be provided.
A method which handles a corresponding case when a channel suffers from intersymbol interference is discussed by Erik Lindskog et al. in the reference entitled xe2x80x9cA Transmit Diversity Scheme For Channels With Intersymbol Interference,xe2x80x9d IEEE, International Communication Conference, ICC 2000. As discussed by Lindskog et al., with two transmit antennas and one receive antenna, the same diversity can be achieved as with one transmit and two receive antennas. The disclosures of both the Alamouti and Lindskog et al. references are hereby incorporated herein in their entirety by reference.
According to embodiments of the present invention, methods for receiving transmissions from a diversity transmitter include receiving a first symbol-spaced baseband signal corresponding to first portions of first and second encoded data sequences transmitted over first and second baseband channels, and receiving a second symbol-spaced baseband signal corresponding to second portions of the first and second encoded data sequences transmitted over the first and second baseband channels. The first and second symbol-spaced baseband signals are combined to provide a combined baseband signal, and the combined baseband signal is prefiltered to provide minimum phase channel characteristics. The prefiltered combined baseband signal is equalized to provide an estimate of a data sequence.
By prefiltering the combined baseband signal, the data sequence can be estimated using a reduced complexity equalizer such as a decision feedback estimate equalizer or a reduced state sequence estimate equalizer. Accordingly, overall receiver complexity may be reduced while maintaining receiver performance.